Oil and gas well drilling systems include numerous types of piping, referred to generally as “tubulars.” Tubulars include drill pipes, casings, and other threadably connectable oil and gas well structures. Long strings of joined tubulars are typically used to drill a wellbore or to inhibit or prevent collapse of the wellbore after drilling. Some tubulars are fabricated with male threads on one end and female threads on the other. Other tubulars feature a male thread on either end and connections are made between tubulars using a threaded collar with two female threads. The operation of connecting a series of tubulars together to create a string is known as a “make-up” process, while the reverse is often referred to as a “break-out” process.
When joining lengths of tubulars for oil wells, the nature of the connection between the lengths of tubing is critical. In particular, as the petroleum industry has drilled deeper into the earth during exploration and production, increasing pressures have been encountered. Reliable methods are needed to ensure a good connection.
One connection method involves the connection of two co-operating threaded pipe sections, rotating the pipe sections relative to one another by means of a power tong, measuring the torque applied to rotate one section relative to the other and the number of rotations or turns which one section makes relative to the other. Signals indicative of the torque and turns are fed to a controller that ascertains whether the measured torque and turns fall within a predetermined range of torque and turns that are known to produce a good connection. Upon reaching a torque-turn value within a prescribed minimum and maximum (referred to as a dump value), the torque applied by the power tong is terminated. An output signal, e.g., an audible signal, is then operated to indicate whether the connection is a good or a bad connection.
Current practice often involves make-up of the connection to within a predetermined torque range while plotting the applied torque vs. rotation or time, and then making a visual inspection and determination of the quality of the make-up. This requires a third party interface with a manual human response to stop the make-up process. In many implementations, manual intervention is needed to check for contact between tubulars before rotation for make-up. Some conventional attempts at automation of the make-up process rely on information that is too limited to monitor and confirm that a proper connection has been made. Various conventional make-up techniques are described in U.S. Pat. Nos. 7,712,523; 7,594,540; 7,568,522; 7,296,623; 7,281,587; 7,264,050; 7,100,698; 6,536,520; and 7,896,084.
Accordingly, a need exists for an automated make-up system and methods that ensure a good connection is made while minimizing or eliminating direct human involvement.